Control system



H. D. JAMES AND R. E."DE CAMP.

' CONTROL SYSTEM.

APPLICATION FIILED MAY 12. 1919.

1,392,060. Pawnwdsept. 27,1 21.

WITNESSES: INVENTORS a W gem- J1 James r a .De Camp.

4 UNIT STATE PATEN; OFFICE.

HENRY n. sums, or nnenwoon rm, AND an! E. DE our, 0 WILKINSBUBG, PENNSYLVANIA, .ASSIGNOBS r0 wns'rmonousn mnc'raro a 'nA omcrumN'o conrm, A. CORPORATION OIQPENNSYLVANIA.

CONTROL s'zsrmr. 1

Patented Sept. 27, 1921.

Application and Hay 12,1919. Serial No. 296,597.

To'all whom it may concern Be it known thatwe, HE RY D.- JAMES,

a citizen of the United States, and 'aresident of Edgewood Park in the county of Alleghen and State of Tennsylvimia, and RAY E. n CAMP, a citizen of the United States, and a resident of Wilkinshur in the county of Allegheny and State of ennsyl- Vania, have invented a new and useful Improv'ement in Uontrol Systems, of which the following is a specification.

Our invention relates to mortor-control systems and particularly to systems of the type constituting the subject-matter of a co pIending application by H. D. James, Serial 0. 236,937, filed May .27, 1918, and assigned to the Westinghouse Electric & Manufacturing C0,, and it has for its. object the provision of an improved motor-control sys tem of this character.

Several motor-acceler'atin systems are illustrated in the above appllcation, in each of which the accelerating resistor is adapted to be short-circuited by contactors under the control of relays which are responsive to the voltage drop of a portion or of the whole type constituting the sub'ect-matter of a co-pending application by ay E. De Camp,

Serial No.'241,259, filed June 21, 1918, and

assigned to the westinghouse Electric & 'Manufacturing (10., as shown in Figures 1* and 2 of the above-mentioned James application, or ordinary relays may be employed, as shown in Fig. 6, of the said James appli' cation.

According to the present application, relays of either of the above types may be employed but, if the relay of the above.- referred to De Camp application be adopted, the main releasing: armature, the spring under its control and its associated parts may be dispensedwith. The relay coils are normally energized by line voltage to maintain are diagrammatic views of' control systems embodying our invention A motor having an armature 1 and a shunt field-magnet winding 2, is connected between line conductors 3 and g4, separated by aline contactor 5; An accelerating re sistor 6 is normally in series with the armature 1. The contactor 5 may be closed by a master switch 7 through the medium of an energizing coil 8, upon the master switch 7 i being moved into engagement with a contact member 9. A plurality of contactors 10, 11 and 12 (Figs. 2 and 3) are adapted to be closed to effect the short-circuiting of sections 13, 14 and 15, respectively, of the resistor 6. The contractors 10, 11 and. 12 are under the control of energizing coils 19, 20

and 21, which, in Fig. 2, may be energized when the master switch 7 is moved-into engagement with a contact member 16 and, in Fig. 3, when'the master switch 7 is moved mto engagement with contact member 16,17 and 18, respectively. In the systemof Fig. 1, but two contactors 11 and 12 are employed the energizing coils of which are under the control of a single contact member 16. The v of the resistor. The relays may be of the circuits of the contactor coils are controlled byrelays 25, 26 and 27 (Figs. 2 and 3) having a single energizing coil 22 (Fig. 2) or individual ener izing coils 22, 22 and 22 in circuit with a resistor 59 of high resistance which resistor may, if desired; be omitted. The coils 22, 22, 22 and 22 are normally connected to the line conductors 3 and 4 so as to maintain the relays 25, 26 and 27 in their actuated positions when the motor circuit is open. The relays are shown supplied with springs 30 of different strengths so as to effect the-closing of the corresponding relays in accordance with diiferent values of the current traversing the coil 22 or the coils 22, 22 and 22. These springs may be replaced by their equivalent mechanisms, as described in the two above-referred-to applications.

The relays may be of the type constituting the subj eat-matter of the above-mentioned De Camp application, in which event, a single coil 22 may be employed. Any ordinary relays may be employed, however, and a. single coil or a plurality of coils may be employed, as desired.

.In the system of Figs. 2 and 3, the coil 8 is directly connected across the line conductors 3 and 4: through the master switch 7 and the contact member 9. In the system of Fig. 1, the circuit of the coil 8 comprises also the relay 2 5, and a switch 29 is provided,

"mechanically connected to the contactor 5 so as to establish a holding circuit for the coil 8, following the initial closing of the contactor 5.

, The operation will be first described 111 connection with the system of Fig. 2. The relays 25, 26 and 27 are normally open, as shown. Upon the.actuation of the master switch 7 to its first posit-ion, in which it on gages the cont-act member 9, a circuit is established from the line conductor 3, through the coil 8, the contact member 9 and'the master switch 7, to the line conductor 4. The contactor 5 becomes thereupon closed to establish the motor circuit, which extends from the line conductor 3, through the armature 1 and the resistor 6, and the shunt field- 'magnet winding 2, in parallel, and the con-- tactor 5, to the line conductor 4;. The coil 22 becomes thereupon subjected to the voltage drop of the resistor 6, as it is connected in parallel thereto.

Following the initial acceleration of the motor, the current traversing'the motor-circuit will begin to fall in value, subjecting the coil 22 to a decreasing voltage, the value of which is determined by the value of the current traversing the resistor 6. When this voltage falls to a sufliciently low value,.the relay 25 is closed by its spring 30 (or by gravity, in case the spring is omitted) whereupon, assuming that the master switch 7 has been actuated to its second position, a circuit will be established from the line conductor' 3, through the relay 25, the 'coil 19, the contact member 16 and the master switch 7, to the line conductor 4. The contactor 10 will thereupon become closed, by its actuating coil 19, to effect the short-circuiting of the resistor section 13. Similarly, upon the subsequent closing of the relays 26 and 27, in accordance with the decreasing value of the voltage drop across the resistor 6, the contactors 11 and 12 will become closed to effect the short-circuiting of the resistor sections 14 and 15.

In Fig. 3, the circuits of the coils v19, 20 and 21 are separately controlled by contact members 16, 17 and 18, thereby providing for controlling the speed of the motor. If the master switch 7 be maintained in its first position, the circuit of the coil 19 cannot become closed, so that the motor will be operated at a first low speed. If the master switch 7 be maintained in its-"second position, in engagement with the contact members 9 and 16, the circuit of the coil 19 may be closed when the relay 25'becomes closed, but the circuits of'the coils 20 and 21 will be maintained open, irrespective of ,the positions of the relays 26 and 27, thereby providing for a second speed. In similar fashion,

the cont actor 12 may be maintained open to provide -for a third speed or, if the master switch 7 be actuated to its final position, the operation will be substantially the same as that described above in connection with Fig. 2. v

In the system of Fig. 1,'two. accelerating steps only are provided, but all three relays of the unitary relay structure described in the above-mentioned application by De Camp are employed, one of the relays serving to close the circuit of the coil 8. This circuit extends from the line conductor 3, through the relay 25, (which, unlike the relays 26 and 27, is closed when it occupies its actuated position) the coil 8, the contact member 9 and the master switch 7 to the line conductor 4. Upon the closing of the contactor 5 by its energizing coil 8, the motor circuit is closed and the coils 22, 22", and 22 are energized by the voltage drop of the resistor 6. The opening of the relay 25, uponthe voltage of the resistor 6 falling to a predetermined value, efi'ects the opening of the above-traced circuit of the coil 8. A holding circuit for this coil is, however,

, previously established from the line conductor 3, through the switch 29, the coil 8. the

contact member 9 and the master switch 7, to the line conductor 4. The operation of the relays 26 and 27 to effect the closing of the contactors 11 and 12 is substantially the same as that of the corresponding parts of the. systems of Figs. 2 and 3.-

According to our present invention,therefore, the relays that control the resistorshort-circuiting contactors are maintained open by line voltage to insure the resistor 6 being in circuit with the armature 1 at the time that the motor circuit is closed by the contactor 5. Upon the closing of the motor circuit, however, the control of the relays is transferred to the resistor 6, their subsequent operation being substantially the same as that described in the aforementioned application by James. The necessity for the maintaining spring and the releasing annature of the above-referred-to De Camp relay is thus eliminated.

Obvious and desirable modifications will occur to those skilled in the art. W e desire, therefore, that the appended claims shall be construed broadly, except in so far as limitations may be-specifically imposed therein.

We claim as our invention:

1. The combination with an electric motor having an armature,'a resistor in series therewith, a switch for short-circuiting said resistor, a relay for said switch that is biased to closed position and having an opening coil, and a source of energy for said motor, of means whereby the voltage of said source is applied to said coil when said-motor is disconnected from said source and whereby said coil is energized in accordance with the a switch for connecting said motor to said source, of a second relay that is biased to open position and having a closing coil, means normally connecting said coils to said source, and means for closing said connecting switch and thereby connecting the firstnamed coil across said resistor.

3. The combination with an electric motor, a resistor associated therewith and a source of energy, means controlled successively in accordance with the voltage of said source and the voltage drop of said resistor for controlling said resistor, and a switch for closing the circuit of said motor, of a master switch having two positions, in the first of which it effects the closing of said circuit-closing switch and in the second of which it controls said controlling means.

4. The combination with an electric motor having an armature, a resistor in series therewith, a switch for short-circuiting said resistor and having an actuating coil, a relay for said switch having an actuating coil in parallel circuit with said resistor, and a switch for closing the circuit of said motor, of a master switch havingtwo positions, in the first of which it efi'ects the closing of said circuit-closing switch and in the second of which it partly closes the circuit of said switch coil.

5. The combination with an electric motor having an armature, a resistor in series therewith, a switch for short-circuiting said resistor and having an actuating coil, and a switch for closing the circuit of said motor and having an actuating coil, of a pair of relays controlled in accordance with the drop in potential across said resistor forrespectively controlling the circuits of said coils, means for closin first the circuit of said circuit-closing-switch coil through one of said relays and then the circuit of said resistor short circuiting switch coil through said other relay, and means for maintaining said circuit-closing-switch coil energized.

6. The combination with an electric motor having an armature, a resistor in series therewith, a plurality of switches for shortcircuiting said resistor, each having an actuating coil, a relay for each of said switches and having an actuating coil connected across said resistor, and a line switch for closing the circuit of said'motor having an actuating coil, of a master switch for controlling the circuit of the actuating coil of line closing-switch in one of its positions and for partly closing the circuits of said resistor-short-circuiting switch coils in its other position.

7. Thecombination with an electric motor having an armature, a resistor in series therewith, a source of energy for said motor, a plurality of switches for short-circ'uiting said resistor, each having an actuating coil,

and a switch for closing the circuit of said.

motor and having an actuating coil, of a relay .for each of said switches and having an actuating coil connected initially to said source and later across said resistor, and a master switch having a plurality of positions in each of which it controls the circuit of one of said switch coils.

8. The combination with a source of energy, an electric motor, a resistor in circuit therewith and means for controlling said resistor, of. means successively controlled in accordance with the voltage of said source and with the drop in potential across said resistor for controlling said resistorcontrolling means.

9. The combination with a source of energy, an electric motor, a resistor in cir- I cuit therewith and means comprlsing a plurality of switches for controlling said resistor, of means comprising a plurality of relays that are successively controlled in accordance with the voltage of said source and with the drop in potential across-said resistor for controlling said switches, andmeans for initiating the operation of said motor.

10. The combination with a source of energy, an electric motor, a resistor in circuit therewith and means for controllin said resistor, of means successively controlled in accordance with the voltage of said source and with the drop in potential across said resistor for controlling said resistorcontrolling means, and means for initiating the operation of said motor and for effecting the successive control of said resistor-controlling means.

Intestimony whereof, we have hereunto this 29th day of April, I, I

subscribed our names 1919.

HENRY D; JAMES. RAY E. DE CAMP. 

